Grinding wheel

ABSTRACT

A circular grinding wheel has a center point and defines a multiplicity of extraction holes, which, in particular, are circular extraction holes. The center point of each extraction hole is arranged at the point of intersection of a radial line extending from the center point of the grinding wheel with a circle of holes that is arranged concentrically with respect to the center point and that has a radius. At least one of the radial lines is a single-hole radial line, on which the center point of only a single extraction hole is arranged. The center points of all the extraction holes that are arranged on a single-hole radial line lie substantially on a common single-hole circle having a radius. Each radial line comprises the center point of an extraction hole on at least one radius on which the two radial lines that are adjacent to this radial line in the circumferential direction have no center point of an extraction hole.

PRIOR ART

The present invention relates to a circular grinding disk comprising a multiplicity of extraction holes according to the preamble of claim 1. Such grinding disks are also known as “multihole grinding disks”.

Machining a workpiece with a rotating grinding disk generates grinding dust, which without further measures would clog the grinding disk and therefore lead to short service lives. The grinding disk must therefore be changed frequently, which is extremely laborious and uneconomical.

To overcome this problem, grinding disks with extraction holes that pass through the grinding surface have long been known. The grinding dust can be discharged through these extraction holes. These grinding disks may be fastened to grinding pads, which likewise have corresponding extraction holes. This discharge is particularly effective if the grinding dust is actively extracted by producing a negative pressure in the grinding pad.

Such grinding disks of the generic type are known for example from EP 1 977 858 A1. The grinding disks disclosed there have a multiplicity of extraction holes through which the dust can be extracted. On account of the special arrangement of the extraction holes (known as the “pattern of holes”), extraction of the grinding dust is possible virtually independently of the relative rotational position between the grinding disk and the grinding pad. Further grinding disks of the generic type with other patterns of holes are known for example from WO 2008/042775 A1, where an arrangement of the extraction holes at the corner points of a triangular grid is described, or from EP 781 629 A1, where the extraction holes are arranged at the corner points of a square grid.

The pattern of holes should satisfy a great many criteria simultaneously. On the one hand, the overall surface area of all the extraction holes should be large enough that extraction can take place in the first place. On the other hand, however, the overall surface area of all the extraction holes must not be too large, in order that a sufficient amount of abrasive particles can be arranged on the remaining grinding surface to ensure removal of material in the first place.

Moreover, it is desirable for practical reasons that the grinding disk can be fastened to as many different grinding pads as possible, the pattern of holes of which may vary greatly from supplier to supplier. There should at the same time always be a sufficient overlap between the extraction holes of the grinding disk and those of the grinding pad. Furthermore, it is desirable that the extraction capacity is substantially independent of the relative rotational position between the grinding disk and the grinding pad; the user then no longer has to laboriously bring the extraction holes of the grinding disk and the grinding pad into line with one another.

Finally, the distance between the holes should also on the one hand not be chosen to be too great, since otherwise uniform extraction is not possible. On the other hand, however, the distance between the extraction holes must also not be too small, since the grinding disk could otherwise lose its stability and, for example, could break or tear at the areas between the extraction holes.

It is therefore an object of the present invention to provide a grinding disk with which as good a compromise as possible between the aforementioned effects can be achieved. In particular, it is therefore intended that the greatest and most uniform possible extraction can be performed, largely independently of the pattern of holes of the grinding pad used and the relative rotational position between the grinding disk and the grinding pad.

DISCLOSURE OF THE INVENTION Advantages of the Invention

These and other objects are achieved by a circular grinding disk with a center point and a multiplicity of extraction holes, in particular circular extraction holes. The grinding disk may have a fastening opening, in particular a circular fastening opening, at its center. In this case, the center point should be understood as meaning only an imaginary reference point, from which the geometrical arrangement of extraction holes described below is defined. In any event, the center point of the grinding disk is understood as meaning the geometrical center point of the circular circumference of the grinding disk.

Each extraction hole is assigned a center point of its own. This center point is likewise an imaginary reference point of the grinding disk, which corresponds to the geometrical center of gravity of the extraction hole. If the extraction hole is circular, for example, its center point coincides with the geometrical center point of the circle that forms the periphery of the extraction hole.

The center point of each extraction hole defines on the one hand a radial line which extends from the center point of the grinding disk and on which the center point of the extraction hole lies. On the other hand, the center point of the extraction hole defines a circle of holes, which is concentric to the center point of the grinding disk and on which the center point of the extraction hole lies. Therefore, the center point of the extraction hole then lies on the point of intersection of the radial line with the circle of holes.

According to the invention, the arrangement of the extraction holes is characterized by the following properties: firstly, on at least one radial line extending from the center point, only the center point of a single extraction hole is arranged. Such a radial line is referred to here and hereafter as a single-hole radial line.

Furthermore, the center point of all the extraction holes that are arranged on a single-hole radial line are intended to lie substantially on a common single-hole circle with the same radius. They are consequently all at substantially the same distance from the center point of the grinding disk. The word “substantially” means here that the distances between the center point of the extraction area from the center point of the grinding disk differ from one another at most by half a diameter of the individual extraction holes. The above property does not exclude the possibility that the center points of extraction holes that are not arranged on a single-hole radial line also lie on the single-hole circle. However, at least one of the extraction holes on the single-hole circle must at the same time lie on a single-hole radial line.

Finally, it is intended that each radial line comprises the center point of an extraction hole on at least one radius on which the two radial lines that are adjacent to the radial line in the circumferential direction have no center point of an extraction hole.

The combination of these features leads to a particularly good compromise between extraction capacity and uniformity, independence from the pattern of holes of the grinding pad and the positioning and stability of the grinding disk. The arrangement of the extraction holes that lie both on a single-hole radial line and on the single-hole circle ensures, for example, that the extraction holes are offset in relation to one another in the circumferential direction. As a result, a relatively uniform arrangement of the extraction holes is achieved, without the extraction holes having to lie too close together to reduce the stability of the grinding disk. In addition, it has been found that, by such a pattern of holes, the removal capacity (that is to say the amount of material removed from a machined surface during grinding per unit of time) can be increased significantly. Furthermore, it has been found in many tests that the roughness of the machined surface remains virtually unchanged.

In preferred embodiments, the number of circles of which the radius is smaller than the radius of the single-hole circle lies in the range from 2 to 5. In other words, the single-hole circle is therefore the third-smallest, fourth-smallest, fifth-smallest or sixth-smallest radius on which extraction holes are arranged. Preferably, the number of circles of which the radius is smaller than the radius of the single-hole circle is 3 or 4. The more circles of holes lie within the single-hole circle, the further out the single-hole circle lies. In these regions of the grinding surface that are situated further out, the angular offset described above is particularly favorable.

Each radial line that has at least one center point of an extraction hole may be assigned to a radial line type. By definition, this radial line type indicates the entirety of the radii on which the center point of an extraction hole is arranged on this radial line. For example, a radial line type could be characterized in that a first hole is arranged on the smallest radius, a second hole is arranged on the third-smallest radius and a third hole is arranged on the fifth-smallest radius.

Preferably, the grinding disk has at most 5, preferably at most 4, more preferably at most 3, particularly preferably precisely 3, different radial line types. One of these radial line types is in this case always the radial line type of the single-hole radial lines. Since, according to the invention, the center points of all the extraction holes that are arranged on a single-hole radial line lie substantially on a common single-hole circle, the grinding disk comprises just one single-hole radial line type. As a consequence of the properties according to the invention, the other radial line types always comprise at least the center points of two extraction holes.

Preferably, at most 6, preferably at most 4, particularly preferably at most 3 center points of extraction holes are arranged on each radial line. As a result, it can be ensured that the distances of the extraction holes from one another are great enough to ensure the stability of the grinding disk.

Likewise preferably, the center point of at least 3 extraction holes are arranged on each radial line that is not a single-hole radial line. In other words, there are therefore no radial line types that comprise precisely two extraction holes. This has the effect that the grinding disk contains a sufficient number of extraction holes.

It has proven to be favorable if the number of all the extraction holes lies in the range from 20 to 100, preferably from 30 to 80, particularly preferably from 40 to 64. This provides a good compromise between great and uniform extraction and at the same time stability of the grinding disk.

The number of radial lines that comprise at least one center point of an extraction hole advantageously lies in the range from 10 to 50, preferably between 20 and 30, and is particularly preferably 24. A smaller number of radial lines would mean an accumulation of the extraction holes in certain regions of the grinding disk, which would lead to extraction that is not uniform. A greater number of radial lines would lead to a high density of the extraction openings, which would reduce the stability of the grinding disk.

Likewise preferably, the number of circles of holes on which the center point of at least one extraction hole is arranged lies in the range from 3 to 10, preferably from 4 to 8, particularly preferably from 4 to 6. Too small a number of circles of holes would lead to extraction that is not uniform along the radial direction. By contrast, too great a number would bring about a loss of stability in the radial direction.

Preferably, the radii of the circles of holes are distributed substantially uniformly over the radius of the grinding disk as a whole. The smallest radius of a circle of holes may be between 15% and 35%, preferably between 20% and 30%, of the radius of the grinding disk. The largest radius of a circle of holes may be between 70% and 90%, preferably between 75% and 85%, of the radius of the grinding disk. The average absolute deviation of the radial distances respectively between two adjacent circles of holes may be used for characterizing the uniform distribution of the radii. Preferably, this average absolute deviation is less than 30%, preferably less than 15%, of the average radial distance between two adjacent circles of holes.

The average number of extraction holes of which the center points lie on a radial line preferably lies in the range from 1.2 to 3, preferably from 1.4 to 2.85, particularly preferably from 1.6 to 2.7. A smaller average number would lead to extraction that is not uniform along the radial direction, while a greater average number would reduce the stability of the grinding disk.

Likewise preferably, the average number of extraction holes of which the center points lie on a circle of holes preferably lies in the range from 6 to 20, preferably from 8 to 15, particularly preferably from 10 to 12.5. A smaller average number would lead to extraction that is not uniform along the circumferential direction, while a greater average number would reduce the stability of the grinding disk.

As already explained above, the ratio of the total area of all the extraction holes to the total area of the grinding disk determines on the one hand the effect of the extraction and on the other hand the stability of the grinding disk. This ratio advantageously lies in the range from 2% to 20%, preferably from 6% to 12%, particularly preferably from 4% to 7%. The total area of the grinding disk comprises both the actual grinding area in which the grinding particles are attached and the total area of all the extraction holes. If the grinding disk has a central fastening opening, however, the surface area thereof is not included in the total area of the grinding disk. Therefore, if the grinding disk has a diameter D and has a central, circular fastening opening with a diameter b, the total area of the grinding disk is by definition calculated by

$\frac{\Pi}{4}{\left( {D^{2} - b^{2}} \right).}$

In advantageous embodiments, at least 80%, preferably at least 90%, particularly preferably all, of the extraction holes are circular and have a diameter which lies in the range from 3 mm to 6 mm, preferably from 3.5 mm to 4.5 mm, particularly preferably from 4 mm to mm. With such diameters, it has been possible to achieve particularly good extraction.

Preferably, the center points of at least 8 extraction holes, preferably of precisely 8 extraction holes or precisely 16 extraction holes, are arranged on each circle of holes.

Advantageously, on each circle of holes, the extraction holes are arranged uniformly in the circumferential direction. If a circle of holes comprises 8 extraction holes, for example, two extraction holes that are arranged on the circle of holes and adjacent to one another in the circumferential direction are arranged at an angular distance of 45° from one another.

It is advantageous if the arrangement of the extraction holes is not substantially translationally symmetrical. An arrangement is referred to as translationally symmetrical here if it is invariant under linear translation. The word “substantially” means here that, on account of the finite number of extraction holes in the peripheral regions of the grinding disk, the arrangement is not completely invariant under such a translation. Substantially translationally symmetrical arrangements of the extraction holes are, for example, the arrangement at the corner points of a square grid (as in EP 781 629 A1) or at the corner points of a triangular grid (as in WO 2008/042775 A1).

The grinding disk may comprise any substrate known per se, for example paper or vulcan fiber. The extraction holes may be produced, for example, by punching into the substrates. The abrasive particles may be any known per se, for example alumina, silicon carbide or silicon nitride. The abrasive particles may have customary particle sizes, for example P80, P180, P240 or P400. The abrasive particles may be fixed on the substrate by a binder that is likewise known per se.

Alternatively or in addition to a central fastening opening, the grinding disk may have on its rear side (i.e. on the side facing away from the abrasive particles) further fastening means for fastening to a grinding pad. For example, these may be loops and/or hooks of a loop-hook fastening, that is to say a Velcro fastening. It is likewise conceivable that the fastening means are formed by a coating with a pressure-sensitive adhesive.

The following Table 1 shows particularly preferred combinations of parameters that describe the arrangement of the extraction holes:

TABLE 1 Parameter 1 2 3 4 5 6 Diameter of the 150 150 150 125 150 150 grinding disk in mm Diameter of the 4 4.5 5 4.5 4 4.5 extraction holes in mm Number of 56 56 56 40 64 64 extraction holes Number of 5 5 5 4 6 6 circles of holes Number of 8 8 8 8 8 8 extraction holes 8 8 8 8 8 8 on the circles 16 16 16 16 8 8 of holes 8 8 8 8 16 16 16 16 16 8 8 16 16 Number of 3 3 3 3 4 4 circles of holes of which the radius is smaller than the radius of the single-hole circle Number of radial 3 3 3 3 3 3 line types Numbers of 1; 1; 3 1; 1; 3 1; 1; 3 1; 1; 3 1; 3; 4 1; 3; 4 extraction holes on the radial line types

DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below on the basis of six actual exemplary embodiments and figures, which embody the above variants. In the drawings:

FIG. 1 shows a first exemplary embodiment of a grinding disk according to the invention, with 56 extraction holes with a diameter of 4 mm;

FIG. 2 shows a second exemplary embodiment of a grinding disk according to the invention, with 56 extraction holes with a diameter of 4.5 mm;

FIG. 3 shows a third exemplary embodiment of a grinding disk according to the invention, with 56 extraction holes with a diameter of 5 mm;

FIG. 4 shows a fourth exemplary embodiment of a grinding disk according to the invention, with 40 extraction holes with a diameter of 4.5 mm;

FIG. 5 shows a fifth exemplary embodiment of a grinding disk according to the invention, with 64 extraction holes with a diameter of 4 mm;

FIG. 6 shows a sixth exemplary embodiment of a grinding disk according to the invention, with 64 extraction holes with a diameter of 4.5 mm.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The first embodiment, represented in FIG. 1, shows a circular grinding disk 1 with a diameter D=150 mm. Arranged at the center of the grinding disk 1 is a circular fastening opening 3 with a diameter of b=16 mm, by means of which the grinding disk 1 can be connected in a way known per se to a grinding pad that is not represented here. The grinding disk 1 contains an imaginary center point M, which represents the geometrical center point of the circular outer circumference 4 of the grinding disk 1.

The grinding disk 1 contains a total of n_(L)=56 circular extraction holes 2 with a diameter of 4 mm. The center point of each extraction hole 2 is arranged both on one of n_(S)=24 radial lines extending from the center point M and on one of n_(K)=5 circles of holes K₁, . . . , K₅ with associated radii r₁=18.5 mm, r₂=27.5 mm, r₃=40 mm, r₄=50 mm and r₅=60 mm. Arranged on the circles of holes K₁, . . . , K₅ are the center points of n_(L1)=8, n_(L2)=8, n_(L3)=16, n_(L4)=8 and n_(L5)=16 extraction holes 2, respectively. On each of the circles of holes K₁, . . . , K₅, the extraction holes 2 are respectively arranged uniformly in the circumferential direction: the extraction holes 2 on the circles of holes K₁, K₂ and K₄ are therefore arranged at an angular distance of 45° from one another, while the extraction holes 2 on the circles of holes K₃ and K₅ are arranged at an angular distance of 22.5° from one another.

The eight radial lines S₂, S₈, S₈, S₁₁, S₁₄, S₁₇, S₂₀ and S₂₃ respectively comprise only the center point of a single extraction hole 2. These radial lines are therefore referred to as single-hole radial lines. The altogether 8 extraction holes 2 on the single-hole radial lines all lie on the same circle of holes K₄ and are consequently all at the same distance from the center point M of the grinding disk 1. The circle of holes K₄ is therefore referred to as a single-hole circle. The three circles of holes K₁, K₂ and K₃ therefore have smaller radii than the single-hole circle K₄.

As FIG. 1 also reveals, each radial line S₁, . . . , S₂₄ comprises the center point of an extraction hole 2 on at least one radius on which the two radial lines that are adjacent to this radial line in the circumferential direction have no center point of an extraction hole 2. For example, the radial line S₁ on the radius r₂ comprises the center point of an extraction hole 2, which therefore lies on the circle of holes K₂. However, the radial lines S₂ and S₂₄ that are adjacent in the circumferential direction do not comprise an extraction hole 2 at this distance r₂. The radial line S₂ comprises the center point of an extraction hole 2 on the radius r₄, but the radial lines that are adjacent in the circumferential direction, S₁ and S₃, do not. This has the effect that the extraction holes 2 are angularly offset in relation to one another. In this way, on the one hand the extraction holes 2 are arranged relatively uniformly and make relatively uniform extraction possible. On the other hand, the distances between the extraction holes 2 are great enough to prevent tearing or breaking of the areas between adjacent extraction holes 2.

The grinding disk 1 comprises precisely three radial line types T₁, T₂ and T₃: The radial line type T₄ comprises only a single extraction hole 2, on the radius r₄, and therefore forms a single-hole radial line. The radial line type T₂ comprises an extraction hole 2 on the radii r₂, r₃ and r₅, while the radial line type T₃ comprises an extraction hole 2 on the radii r₁, r₃ and r₅. Each of the radial lines S₁, S₂, . . . and each of the radial line types T₁, T₂, T₃ therefore respectively comprises either precisely one or precisely three center points of extraction holes 2. The radial line types are arranged in the circumferential direction U in the sequence T₂, T₁, T₃, this sequence being repeated eight times over the entire angular range of 360°. The angle between T₂ and T₁ and between T₂ and T₁ is 11.25°, while that between T₁ and T₃ is in each case 22.5°. The arrangement of the extraction holes 2 is invariant under rotation about the center point M by 45°, therefore has an eightfold symmetry.

The grinding disk 1 represented in FIG. 1 has a total area

$A = {{\frac{\Pi}{4}\left\lbrack {\left( {150\mspace{14mu} {mm}} \right)^{2} - \left( {16\mspace{14mu} {mm}} \right)^{2}} \right\rbrack} = {174701\mspace{14mu} {{mm}^{2}.}}}$

Each of the extraction holes 2 has an area of

${a = {{\frac{\Pi}{4}\left( {4\mspace{14mu} {mm}} \right)^{2}} = 12}},{57\mspace{14mu} {{mm}^{2}.}}$

Consequently, the ratio of the total area of all the extraction holes 2 to the total area A of the grinding disk 1 is approximately

${\frac{56 \cdot \left( {4\mspace{14mu} {mm}} \right)^{2}}{\left( {150\mspace{14mu} {mm}} \right)^{2} - \left( {16\mspace{14mu} {mm}} \right)^{2}} = 4},{03{\%.}}$

The average distance between two adjacent circles of holes in FIG. 1 is 10.375 mm. The average absolute deviation of this average distance is 1.0625 mm. Consequently, the average absolute deviation is approximately 10% of the average radial distance.

FIGS. 2 and 3 show a second and third exemplary embodiment, respectively, which differ from the first exemplary embodiments merely by the diameter of the extraction holes 2: in the second exemplary embodiment according to FIG. 2, this diameter is d=4.5 mm, while in the third exemplary embodiment, shown in FIG. 3, it is d=5 mm.

The fourth exemplary embodiment, presented in FIG. 4, is a further modification of that represented in FIG. 2. By contrast with FIG. 2, the grinding disk 1 of FIG. 4 has a diameter of D=125 mm, and the diameter of the central fastening opening is 12 mm. Furthermore, it has only four circles of holes K₁, . . . , K₄, the arrangement and radii of which correspond to those in FIG. 2. However, the grinding disk 1 shown in FIG. 4 does not comprise a fifth circle of holes.

FIGS. 5 and 6 show further exemplary embodiments, with in each case 6 circles of holes K₁, . . . , K₆ and associated radii r₄, . . . , r₆. In the case of this exemplary embodiment, the numbers of holes on the circles of holes are n_(L1)=n_(L2)=n_(L3)=n_(L5)=8 and n_(L5)=n_(L6)=16. The grinding disks 1 represented in FIGS. 5 and 6 also have n_(S)=24 radial lines, which belong to three radial line types T₁, T₂, T₃: The radial line type T₁ comprises only a single extraction hole 2, on the radius r₅, and therefore forms a single-hole radial line. The radial line type T₂ comprises an extraction hole 2 on the radii r₂, r₄ and r₆, while the radial line type T₃ comprises an extraction hole 2 on the radii r₄, r₂, r₄ and r₆. Each of the radial lines S₁, S₂, . . . or each of the radial line types T₁, T₂, T₃ therefore comprises either precisely one, precisely three or precisely four center points of extraction holes 2. The radial line types are arranged in the circumferential direction U in the sequence T₂, T₁, T₃, this sequence being repeated eight times over the entire angular range of 360°. The angle between T₂ and T₄ and between T₂ and T₄ is 11.25°, while that between T₄ and T₃ is in each case 22.5°. The arrangement of the extraction holes 2 is invariant under rotation about the center point M by 45°, therefore has an eightfold symmetry.

The parameters for the embodiments described above are compiled in the following Table 2:

TABLE 2 Parameter FIG. 1 FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 6 Diameter D of 150 150 150 125 150 150 the grinding disk 1 in mm Diameter of the 16 16 16 12 16 16 central fastening opening in mm Total area A of 17470 17470 17470 12158 17470 17470 the grinding disk 1 in mm² Diameter d of 4 4.5 5 4.5 4 4.5 the extraction holes 2 in mm Diameter of the 16 16 16 12 16 16 central fastening opening 3 in mm Number n_(L), of 56 56 56 40 64 64 extraction holes 2 Number n_(K) of 5 5 5 4 6 6 circles of holes Radii r₁, r₂, . . . 18.5 18.5 18.5 18.5 17.5 17.5 of the circles 27.5 27.5 27.5 27.5 25 25 of holes in mm 40 40 40 40 28.75 28.75 50 50 50 50 40 40 60 60 60 50 50 60 60 Numbers n_(K1), n_(K2), 8 8 8 8 8 8 . . . of extraction 8 8 8 8 8 8 holes 2 on the 16 16 16 16 8 8 circles of holes 8 8 8 8 16 16 16 16 16 8 8 16 16 Radius r_(i), of the 50 50 50 50 50 50 single-hole circle in mm Number of 3 3 3 3 4 4 circles of holes of which the radius is smaller than the radius of the single-hole circle Number n_(S) of 24 24 24 24 24 24 radial lines Number of radial 3 3 3 3 3 3 line types Numbers of 1; 1; 3 1; 1; 3 1; 1; 3 1; 1; 3 1; 3; 4 1; 3; 4 extraction holes 2 on the radial line types Average number 11.20 11.20 11.20 10.00 10.67 10.67 of extraction holes 2 per circle of holes n_(L),/n_(K) Average number 2.33 2.33 2.33 1.67 2.67 2.67 of extraction holes 2 per radial line n_(L)/n_(S) Ratio of the 4.0% 5.1% 6.3% 5.2% 4.6% 5.8% total area of all the extraction holes 2 to the total area (A) of the grinding disk 1

The grinding disks according to the invention allow grinding dust to be transported away efficiently. As a result, the service life of the grinding disk can be extended significantly, so that the grinding disks are consumed less quickly and therefore have to be changed less frequently. 

1. A circular grinding disk comprising a body defining a center point and a multiplicity of extraction holes, wherein the center point of each extraction hole is arranged at the point of intersection of a radial line extending from the center point of the grinding disk with a circle of holes that is arranged concentrically with respect to the center point of the grinding disk and that has a radius, wherein at least one of the radial lines is a single-hole radial line on which the center point of only a single extraction hole is arranged, wherein the center points of all of the extraction holes that are arranged on a single-hole radial line lie substantially on a common single-hole circle with a radius radius, and wherein each radial line comprises the center point of an extraction hole on at least one radius on which the two radial lines that are adjacent to this radial line in the circumferential direction have no center point of an extraction hole.
 2. The grinding disk as claimed in claim 1, wherein the number of circles of holes of which the radius is smaller than the radius of the single-hole circle lies in the range from 2 to
 5. 3. The grinding disk as claimed in claim 1, wherein: each radial line is assigned to a radial line type, which indicates the amount of radii on which the center point of an extraction hole is arranged on this radial line and wherein the grinding disk has at most 5, different radial line types.
 4. The grinding disk as claimed in claim 1, wherein at most 6 center points of extraction holes are arranged on each radial line.
 5. The grinding disk as claimed in claim 1, wherein the center points of at least 3 extraction holes are arranged on each radial line that is not a single-hole radial line.
 6. The grinding disk as claimed in claim 1, wherein the number of all the extraction holes lies in the range from 20 to 100 .
 7. The grinding disk as claimed in claim 1, wherein the number of radial lines that comprise at least one center point of an extraction hole lies in the range from 10 to
 50. 8. The grinding disk as claimed in claim 1, wherein the number of circles of holes on which the center point of at least one extraction hole is arranged lies in the range from 3 to
 10. 9. The grinding disk as claimed in claim 1, wherein the average number of extraction holes of which the center points lie on a radial line lies in the range from 1.2 to
 3. 10. The grinding disk as claimed in claim 1, wherein the average number of extraction holes of which the center points lie on a circle of holes lies in the range from 6 to
 20. 11. The grinding disk as claimed in claim 1, wherein the ratio of the total area of all the extraction holes to the total area of the grinding disk lies in the range from 2% to 20%.
 12. The grinding disk as claimed in claim 1, wherein at least 80% of the extraction holes are circular and have a diameter which lies in the range from 3 mm to 6 mm.
 13. The grinding disk as claimed in claim 1, wherein the center points of at least 8 extraction holes are arranged on each circle of holes.
 14. The grinding disk as claimed in claim 1, wherein on each circle of holes, the extraction holes are arranged uniformly in the circumferential direction.
 15. The grinding disk as claimed in claim 1, wherein the arrangement of the extraction holes is not substantially translationally symmetrical.
 16. The grinding disk as claimed in claim 1, wherein the extraction holes are circular extraction holes.
 17. The grinding disk as claimed in claim 2, wherein the number of circles of holes of which the radius is smaller than the radius of the single-hole circle is 3 or
 4. 18. The grinding disk as claimed in claim 3, wherein the grinding disk has at most 3 different radial line types.
 19. The grinding disk as claimed in claim 4, wherein at most 3 center points of extraction holes are arranged on each radial line.
 20. The grinding disk as claimed in claim 6, wherein the number of all extraction holes lies in the range from 40 to
 64. 